Systems, Methods and Apparatuses for Prevention of Relay Attacks

ABSTRACT

The systems, methods and apparatuses described herein provide an apparatus configured for preventing relay attacks on a communication link between the apparatus and a communication partner. The apparatus may comprise a communication port, a timer and a processor. The processor may be configured to generate a request, transmit the request through the communication link using the communication port and start counting time using the timer, receive a response via the communication port and stop the timer, receive authentication data via the communication port, authenticate the authentication data, compare the counted time with a predefined threshold, compare a first field within the request with a second field within the response and determine whether there is a relay attack.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/274,290, filed Sep. 23, 2016, which is a continuation of U.S.application Ser. No. 14/487,778, filed Sep. 16, 2014, which claimspriority to U.S. Provisional Application No. 61/878,938, filed Sep. 17,2013, each of which is entitled “SYSTEMS, METHODS AND APPARATUSES FORPREVENTION OF RELAY ATTACKS,” the content of each of which isincorporated herein by reference in their entirety.

FIELD OF THE DISCLOSURE

The systems, methods and apparatuses described herein relate to theauthentication of a device.

BACKGROUND

A number of systems rely on proximity of communicating devices forpayment processing. For example, contactless payment systems rely on theassumption that a valid user's payment device (such as a smartphone witha payment application, or a payment smartcard) is in proximity to theterminal when the payment is done. Typically, communication mechanismsuch as Near Field Communication (NFC) are commonly used to verify thatcommunicating devices are in proximity to payment terminals. While suchcommunication mechanism impose restrictions on the distance betweencommunicating devices according to physical properties (for example, NFCoperates at distances on the order of centimeters only), systems relyingon such communication mechanism are still vulnerable to relay attacks(also called in the art as “mafia-in-the-middle attacks” or “mafia fraudattacks”).

In a common scheme, an attacker may use a specially constructed orconfigured fake device (i.e., an attacker's device) to mislead a paymentterminal to communicate with the attacker's device. The attacker'sdevice may in turn be connected to a remote terminal under control ofthe attacker (i.e., an attacker remote terminal). The attacker's devicemay communicate the information it receives from the payment terminal tothe attacker remote terminal using any communication link suitable forthe attacker. The attacker remote terminal may in turn be positioned tocommunicate with a legitimate device. Then, attacker's device mayreceive information from legitimate payment terminal, relay it to theattacker remote terminal, which in turn may pass this information to thelegitimate device; at the same time, the attacker remote terminal mayreceive information from legitimate device, relay it to the attacker'sdevice, which in turn may pass this information to the legitimateterminal.

Consequently, during an attack, while the legitimate terminal may appearto be directly communicating with a legitimate device that is in closephysical proximity to the legitimate terminal, it in fact may beexchanging information with a legitimate device physically located inany arbitrary location (e.g., at a different place in the same room, ata different room, or even many hundreds or thousands of kilometersaway). It should be noted that for this type of attack, attacker doesn'tneed to interfere with (or to understand) the data exchanged between thelegitimate device and legitimate terminal, and therefore, this attackcannot be prevented by means such as encrypting data stream between thelegitimate device and legitimate terminal.

Therefore, there is a need in the art for detecting and/or preventingsuch attacks.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary system according to thepresent disclosure.

FIG. 2A is a block diagram of another exemplary system according to thepresent disclosure.

FIG. 2B is a flow diagram illustrating an exemplary process forauthenticating a device according to the present disclosure.

FIG. 2C is a flow diagram illustrating another exemplary process for adevice to be authenticated according to the present disclosure.

FIG. 3A is a block diagram of another exemplary system according to thepresent disclosure.

FIG. 3B is a flow diagram illustrating an exemplary process forauthenticating a device according to the present disclosure.

FIG. 3C is a flow diagram illustrating another exemplary process for adevice to be authenticated according to the present disclosure.

FIG. 4A is a block diagram of another exemplary system according to thepresent disclosure.

FIG. 4B is a flow diagram illustrating an exemplary process forauthenticating a device according to the present disclosure.

FIG. 4C is a flow diagram illustrating another exemplary process for adevice to be authenticated according to the present disclosure.

FIG. 5A is a block diagram of another exemplary system according to thepresent disclosure.

FIG. 5B is a flow diagram illustrating an exemplary process forauthenticating a device according to the present disclosure.

FIG. 5C is a flow diagram illustrating another exemplary process for adevice to be authenticated according to the present disclosure.

FIG. 6A is a block diagram of another exemplary system according to thepresent disclosure.

FIG. 6B is a flow diagram illustrating an exemplary process forauthenticating a device according to the present disclosure.

FIG. 6C is a flow diagram illustrating another exemplary process for adevice to be authenticated according to the present disclosure.

FIG. 7 is a flow diagram of another exemplary method according to thepresent disclosure.

DETAILED DESCRIPTION

Certain illustrative aspects of the systems, apparatuses, and methodsaccording to the present invention are described herein in connectionwith the following description and the accompanying figures. Theseaspects are indicative, however, of but a few of the various ways inwhich the principles of the invention may be employed and the presentinvention is intended to include all such aspects and their equivalents.Other advantages and novel features of the invention may become apparentfrom the following detailed description when considered in conjunctionwith the figures.

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention. Inother instances, well known structures, interfaces, and processes havenot been shown in detail in order not to unnecessarily obscure theinvention. However, it will be apparent to one of ordinary skill in theart that those specific details disclosed herein need not be used topractice the invention and do not represent a limitation on the scope ofthe invention, except as recited in the claims. It is intended that nopart of this specification be construed to effect a disavowal of anypart of the full scope of the invention. Although certain embodiments ofthe present disclosure are described, these embodiments likewise are notintended to limit the full scope of the invention.

The present disclosure provides systems, methods and apparatuses fordetecting a relay attack. In one non-limiting example, an apparatusaccording to the present disclosure may have a communication port, and aprocessor configured to establish a communication link with a device viathe communication port, obtain a list of WiFi service set identifiers(SSIDs) from the device, compare the list of WiFi SSIDs to a list ofWiFi SSIDs compiled at the apparatus and determine whether the device isin proximity to the apparatus based on the comparison.

In another embodiment, an apparatus according to the present disclosuremay have two communication ports, and a processor configured toestablish a first and second communication links with a device via thefirst and second communication ports respectively, send a first datasegment via the first communication link and a second data segment viathe second communication link, receive a reply from the device via thefirst communication link, and process the reply to determine if there isan unreasonable delay in either of the two communication links.

In yet another embodiment, an apparatus according to the presentdisclosure may have a communication port, and a processor configured toestablish a communication link with a device via the communication port,obtain from the device a first list of relay attack detection methodssupported by the device, create a second list of relay attack detectionmethods implemented by the apparatus and supported by the device,perform the relay attack detection methods in the second list, anddetermine whether there is a relay attack on the communication linkbased on the relay attack detection results.

FIG. 1 shows an exemplary system 100 according to the presentdisclosure. The system 100 may comprise a device 102 and a terminal 110.The device 102 may comprise a communication port 106 and the terminal110 may comprise a communication port 112. The communications ports 106and 112 may communicate by establishing a communication link 130.Although not shown, each of the device 102 and the terminal 110 mayfurther include hardware elements configured to perform some or allfunctionalities described herein. The hardware elements may includeelectronic circuits, such as Central Processing Units, microprocessors,microcontrollers, field programmable gate arrays (FPGAs), applicationspecific integrated circuits (ASICs), System on a Chip (SoC), or anycombination thereof In some embodiments, the functionalities describedherein may be implemented in hardware configuration. In some otherembodiments, the circuits may be configured to execute software modulesthat implement the functionalities described herein. In yet some otherembodiments, the functionalities described herein may be implemented incombination of hardware and software. Moreover, in some embodiments, theterminal 110 may be a front end of a back end server machine and atleast some of the functionalities described herein may be distributedbetween the terminal 110 and the back end server machine, or thefunctionalities described herein may be performed solely on the back endserver machine and the terminal 110 may be used only to provide thecommunication channel.

The link 130 may be a wireless communication link. For example, thecommunication ports 106 and 112 may be compatible ultra-short range(e.g., NFC or capacitance-based transceivers) communication ports thatmay be used to establish a wireless communication link 130 when thecommunication ports 106 and 112 are physically within a distancesufficient to establish a communication link. Those with skill in theart recognize that this distance may vary depending on the specificcommunication link utilized. In some embodiments, the link 130 may be awired communication link. The wired communication link may be, forexample, USB, IEEE 1394, Unshielded Twisted Pair, co-axial cable, etc.

In some embodiments, the device 102 and the terminal 110 may includeother components, such as WiFi transceivers (not shown), GPS signalreceiver (not shown), 2G/3G communication module, and/or computationmeans (e.g. CPUs or application-specific circuitries; not shown).

It is to be understood that embodiment of the present disclosure may beused by any two electronic devices capable of communicating with oneanother, and that they are not limited to any specific communicationtechnology or implementation. For purposes of illustration only, thedevice 102 may be a mobile device (such as a mobile phone) or awireless-enabled smartcard, and the terminal 110 may be awireless-enabled smartcard reader terminal, or payment terminalaccepting payments from wireless-enabled smartcards and/or fromNFC-enabled smartphones. It is also to be understood that the terminal110 need not be a stationary device and that it, too, may be implementedin a mobile or portable form.

FIG. 2A shows a system 200 according to one embodiment of the presentdisclosure. The system 200 may comprise a device 202, a terminal 210,and one or more WiFi transmitters (214.1 through 214.N, N being anyinteger number). The device 202 may be an embodiment of the device 102and contains all features of the device 102. The terminal 210 may be anembodiment of the terminal 110 and contains all features of the terminal110. The communication port 206 may be an embodiment of thecommunication port 106 and may comprise a WiFi receiver 204. Thecommunication port 212 may be an embodiment of the communication port112 and may comprise a WiFi receiver 208. The communication link 130between the device 202 and terminal 210 may be identical to the link 130shown in FIG. 1. The one or more WiFi transmitters 214.1-214.N may betransmitters in an operational range to the device 202 and terminal 210that both WiFi receivers 204 and 208 can receive their WiFi signals.Some of these WiFi transmitters 214 may be a part of the device 202 orthe terminal 210, while other WiFi transmitters 214 may be external tothe device 202 and terminal 210. For example, some of the WiFitransmitters 214 may be a part of other devices transmitting WiFisignals, which happened to be in an operational range to the device 202and the terminal 210.

FIG. 2B illustrates an exemplary method 220 according to one embodimentof the present disclosure. The method 220 may be used by an embodimentof the terminal 210 to determine whether the device 202 and the terminal210 are located at least within an operating distance of one or moreWiFi transmitters.

At block 222, the terminal 210 may establish the communication link 130with the device 202. The details of establishing such a data connectionmay depend on the particular type of communication link 130 used in aparticular implementation. For example, in some embodiments,establishing the data connection may be initiated by the terminal 210,and in some other embodiments, establishing the data connection may beinitiated by the device 202. In addition, an optional logical channel(such as TCP connection, X.25 connection, Sequenced Packet Exchange(SPX) connection, High-Level Data Link Control (HDLC) connection,SSL/TLS connection over any of these connections, or similar connection;in some embodiments, logical channel may consist of multiple TCPconnections, X.25 connections, Sequenced Packet Exchange (SPX)connections, High-Level Data Link Control (HDLC) connections, SSL/TLSconnections, other similar connections, or combinations of them) may beestablished over the communication link 130. In some other embodiments,equivalent security may be established by alternative means, both knownin the art and developed in the future.

At block 224, the terminal 210 may send a command to the device 202 torequest a set of WiFi service set identifiers (SSIDs) from the device202. For example, the command may request the device 202 to collect someor all SSIDs for WiFi transmitters the device 202 may receive signalfrom.

FIG. 2C is a flow diagram illustrating an exemplary method 240 for thedevice 202 to respond the command with WiFi SSIDs according to thepresent disclosure. As shown in FIG. 2C, at block 242, the device 202may establish the communication link 130 with the terminal 210. Asdescribed above, the details of establishing such a data connection maydepend on the particular type of communication link 130 used in aparticular implementation and an optional logical channel over thecommunication link 130 may be established. At block 244, the device 202may receive the command from the terminal that asks for WiFi SSIDs. Atblock 246, the device 202 may generate a response that contains a listof WiFi SSIDs. The list of WiFi SSIDs may include some or all SSIDs forthe transmitters in an operational range to the device 202 from whichthe device 202 may receive signals. In certain embodiments, the device202 itself may comprise one or more WiFi transmitters and the device 202may include these WiFi SSIDs into the list of the WiFi SSIDs generatedby the device 202. At block 248, the device 202 may send the responsecontaining the list of WiFi SSIDs to the terminal 210. In someembodiments, the response may be sent over the secure communicationchannel.

Referring back to the method 220 in FIG. 2B, at block 226, the terminal210 may compile a list of WiFi SSIDs for transmitters in an operationalrange to the terminal 210 that the terminal 210 may receive signal from.In certain embodiments, the terminal 210 itself may comprise one or moreWiFi transmitters and the terminal 210 may include the WiFi SSIDs forany its own WiFi transmitters into the list of the WiFi SSIDs compiledby the terminal 210. At block 228, the terminal 210 may receive the listof WiFi SSIDs from the device 202. At block 230, the terminal 210 maycompare the received list of WiFi SSIDs to the list of WiFi SSIDscompiled at the terminal 210. At block 232, the terminal 210 maydetermine whether the received list of WiFi SSIDs are the same as thosecompiled at the terminal 210.

If the lists are the same, then at block 234, the terminal 210 maydetermine that the device 202 has passed the proximity verificationbecause the terminal 210 and the device 202 may receive signals from thesame set of WiFi transmitters. The successful proximity verification asdescribed herein may indicate that the link 130 is not under a relayattack.

If, on the contrary, the lists are not the same, the terminal 210 maydetermine that the device 202 has failed the proximity verificationbecause the terminal 210 and the device 202 do not receive signals fromthe same set of WiFi transmitters. For example, if a certain WiFi SSIDis in the list received from the device 202 but not in the list compiledby the terminal 210, this may mean that the device 202 may receive thesignal from the certain transmitter while the terminal 102 cannotreceive a signal from this transmitter. This is unlikely if the terminal210 and the device 202 are in close proximity to each other and thus, inthis case the proximity verification may be deemed as failed. The failedproximity verification as described herein may indicate that the link130 is under a relay attack.

In some embodiments, instead of requiring the received list of WiFiSSIDs are the same as the list of WiFi SSIDs compiled at the terminal210, a threshold value greater than zero may be predetermined. That is,whether the test is considered successful or failed may depend onwhether the number of different SSIDs exceeds this threshold value. Forexample, if the list received from the device 202 has SSIDs A, B, C andthe list compiled at the terminal 210 has SSIDs A, B, D. There are twodifferent SSIDs C and D. If the threshold is 3, then the proximityverification may be deemed as passed and no relay attack is detected. Ifthe threshold value is 2, however, the proximity verification may bedeemed as failed and the link 130 is under a relay attack.

In some other embodiments a threshold value may be a ratio of the numberof different SSIDs to the total number of SSIDs in the list. Forexample, if such a threshold is 1/4, and if there are 9 SSIDs in thelist received from the device 202, and two of them cannot be matched toSSIDs collected by the terminal 210, then the verification may be deemedpassed because the ratio is 2/9, which is less than the threshold value1/4. If the full list of SSIDs is shorter, for instance, consisting of 5SSIDs, the same number of different SSIDs (two) will fail theverification test because the ratio is 2/5, which is larger than thethreshold (1/4).

In some embodiments, in addition to SSIDs, WiFi channel numbersassociated with SSIDs may be additionally sent from the device 202 andchecked at the terminal 210.

In some embodiments, the device 202 may start gathering informationabout SSIDs in advance. For example, terminal 210 may broadcast via WiFithat such information may be requested for authentication purposes.

Also, in some embodiments of the method 220, instead of or in additionto WiFi SSIDs, the terminal 210 may request the device 202 to recordsome information transmitted over a WiFi channel with a specific SSID(or with a specific WiFi channel number). The terminal 210 may alsorecord such information itself, and compare the recorded informationwith that received from the device 202. Such information may include,for example, information from certain WiFi frames transmitted over aWiFi channel with a specific SSID. It should be noted that even if theWiFi frames are encrypted, they can still be used for these purposeswithout being decrypted. As discussed above, if the data, at least inpart, does not match, this may indicate that the terminal 210 and thedevice 202 receive signals from different WiFi transmitters, and,therefore, are not in close proximity to each other and the link 130 isunder a relay attack.

In some embodiments, instead of using any recorded data directly, hashvalues of received WiFi frames (or of certain parts and/or fields ofthese frames) may be computed, recorded, sent from the device 202 to theterminal 210 and compared. In some embodiments, in addition to hashvalues, certain fields of the received WiFi frames may be sent alongwith these hash values. If a particular frame, for example, due tocommunication errors, has not been received successfully, its hash inthe sequence of hash values may be accompanied with a special flagindicating this case. For example, the device 202 may send a sequence ofhash values to the terminal 210, and the terminal 210 may compare thereceived sequence with a sequence the terminal 210 computed itself. Ifthe sequences have identical segments of at least a predefined length(e.g., up to flagged hashes, or up to a pre-defined threshold to allowfor communication errors), the proximity verification may be deemed as asuccess, and the terminal 210 may determine that the terminal 210 andthe device 202 have received signals from the same WiFi transmitter.

In some embodiments, the terminal 210 may comprise one or more WiFitransmitters (not shown on FIG. 2A) and may use these WiFi transmitterto provide WiFi data to be received by the device 202 and sent back overa secure communication channel to the terminal 210. In theseembodiments, the terminal 210 may compare the WiFi data transmitted andreceived to detect a relay attack. This may be used regardless ofwhether there are any activities on other WiFi channels in the vicinity.

It should be understood that, in place of or in addition to WiFi, othermethods of communication, such as BlueTooth, signals from cellularnetwork base stations, GPS satellites, etc. may be used. In such casesboth the terminal 210 and the device 202 may be equipped with respectivecommunication components, such as, for example, BlueTooth receiver,2G/3G communication module, GPS signal receiver, etc. In addition, inplace of WiFi SSIDs, other identifiers may be used. For example,cellular network operator name, channel number or frequency, IDs of GPSsatellites, etc.

It should be noted that methods described with respect to FIG. 2B mayprovide detection of relay attacks with a precision from several metersto several hundred meters. In particular, if WiFi is used, proximity maybe established up to a few dozens of meters.

FIG. 3A shows a system 300 according to another embodiment of thepresent disclosure. The system 300 may comprise a device 302 and aterminal 310. The device 302 may be an embodiment of the device 102 andcontains all features of the device 102 including the communication port106. The terminal 310 may be an embodiment of the terminal 110 andcontains all features of the terminal 110 including the communicationport 112. The communication link 130 between the device 302 and terminal310 may be identical to the link 130 shown in FIG. 1. In addition to thecommunication port 106, the device 302 may further comprise acommunication port 306. The communication port 306 may be a WiFicommunication port and comprise a WiFi receiver or both WiFi transmitterand receiver. In addition to the communication port 112, the terminal310 may further comprise a communication port 312. The communicationport 312 may be a WiFi communication port and comprise both WiFitransmitter and receiver (or a transceiver). Thus, in addition to thecommunication link 130, the device 302 and terminal 310 may alsocommunicate via a communication link 330 established by thecommunication ports 306 and 312. In some embodiments, instead of WiFi,the communication link 330 may use other methods of connection, such asBlueTooth or custom radio wave connection. In these embodiments, insteadof being WiFi communication ports, the communication ports 306 and 312may be other corresponding communication components.

FIG. 3B shows a method 340 according to one embodiment of the presentdisclosure. At block 342, the terminal 310 may establish thecommunication links 130 and 330 with the device 302. The details ofestablishing such data connections may depend on the particular types ofcommunication links 130 and 330 used in a particular implementation. Forexample, in some embodiments, establishing the data connection may beinitiated by the terminal 310, and in some other embodiments,establishing the data connection may be initiated by the device 302 . Inaddition, an optional logical channel, such as described above withrespect to block 222 may be established over either or both of thecommunication links 130 and 330. In some other embodiments, equivalentsecurity may be established by alternative means, known in the artand/or developed in the future.

At block 344, the terminal 310 may send two data segments to the device302 using the link 130 for the first data segment, and link 330 for thesecond data segment. In some embodiments, the first data segment maycomprise a first nonce, and the 2nd data segment may comprise a secondnonce.

FIG. 3C is a flow diagram illustrating an exemplary method 350 for thedevice 302 to respond to the terminal 310 according to the presentdisclosure. As shown in FIG. 3C, at block 352, the device 302 mayestablish the communication links (e.g., 130 and 330) with the terminal310. As described above, the details of establishing such dataconnections may depend on the particular types of communication links130 and 330 used in a particular implementation, and an optional logicalchannel over the communication links 130 and/or 330 may be established.At block 354, the device 302 may receive the first data segment via thecommunication link 130 and the second data segment via the communicationlink 330, and measure a time difference between the moments when the twodata segments are received. At block 356, the device 302 may send areply back to terminal 310, for example, using the communication link130 or using the communication link 330. In some embodiments, the replymay comprise the first nonce from the first data segment, the secondnonce from the second data segment, and the time difference measured inblock 354. In embodiments where a secure channel is established betweenthe terminal 310 and device 302, the reply may be sent over theestablished secure communication channel.

Referring back to the method 340 in FIG. 3B, at block 346, the terminal310 may receive the reply from the device 302. At block 348, theterminal 310 may process the reply to determine whether there is anunreasonable delay in either of the two communication links. Forexample, the terminal 310 may determine whether the nonces received inthe reply match to the first nonce and the second nonce sent to thedevice 302. Also, the terminal 310 may determine whether the timedifference measured by the device 302 is within a predefined threshold.If the nonces do not match, or if the data sent through one link hasbeen received substantially later than the data sent via the other linksuch that the measured time difference is greater than a predefined timedifference, this may indicate that there are delays with datatransmission on the slower link, which, in turn, may indicate that arelay attack has been mounted against that link. In some embodiments,the time difference may be compared with a predefined threshold by thedevice 302 and the comparison result may be included in the reply sentback to the terminal 310.

In some embodiments, instead of using the device 302 to measure the timedifference, the device 302 may echo each of the received data segmentsback to the terminal 310 over the same link through which the datasegment is received, and the time difference may be measured by theterminal 310.

In some embodiments, to avoid measuring the time difference at thedevice 302, alternative embodiments of the methods 340 and 350 may beused. In one alternative embodiment, after sending the first datasegment over the link 130, the terminal 310 may start transmitting dataframes each with a unique identifier using the communication link 330.In some embodiments, each data frame may also contain a different nonce.In addition, the terminal 310 may record the moment each such frame istransmitted. The device 302 may receive the first data segment via thelink 130, and receive a data frame currently being transmitted via thelink 330. In one embodiment, the device 302 may send this frame back tothe terminal 310. In this embodiment, the terminal 310 may use recordedmoments for each frame being sent to determine the duration between thetime when the data segment is transmitted over the link 130 (whichroughly corresponds to transmitting the first frame over the link 330)and the time when that data segment is received by the device 302 (whichroughly corresponds to the time of the frame concurrently received bythe device 302 over the link 330). If the delay determined in such a wayis greater than a predefined threshold, this may indicate that a relayattack has been mounted.

In another alternative embodiment, the data frames sent from theterminal 310 may have timing data embedded therein. For example, theterminal 310 may add to each frame transmitted via the link 330 the timepassed since the first frame of the data segment was sent via the link130 until the current frame is about to be sent via the link 330. Inthis embodiment, using such timing data, the device 302 may determine ifthere is any delay in receiving the data segment via the link 130 andmay conclude whether there is a potential relay attack.

It should be noted that in some alternative embodiments the device 302and the terminal 310 may play the opposite roles by implementing methodssimilar to methods 340 and 350, respectively. In these embodiments, thecommunication port 306 of the device 302 may comprise a WiFitransmitter, and the communication port 312 of the terminal 310 maycomprise a WiFi receiver. The device 302 may implement a method similarto method 340 and may start transmitting data frames each with a uniqueidentifier using the communication link 330 after transmitting the firstdata segment to the terminal 310 over the link 130. The terminal 310 mayimplement a method similar to method 350 and may use the frame receivedvia the link 330 concurrently with the first data segment received viathe link 130 to determine the time period from the first data segmentbeing sent to being received, or may send the frame identifier to thedevice 302 so that the device 302 may determine the time delay inreceiving the data segment over the link 130.

It should be noted that in some embodiments methods 340 and 350 may berepeated more than one time to ensure that delays in data transmissionare not due to occasional communication errors and/or processing errorsat the device 302 and/or the terminal 310.

FIG. 4A shows a system 400 according to another embodiment of thepresent disclosure. The system 400 may comprise a device 402, a terminal410 and a time provider 430. The device 402 may be an embodiment of thedevice 102 and contains all features of the device 102 including thecommunication port 106. The terminal 410 may be an embodiment of theterminal 110 and contains all features of the terminal 110 including thecommunication port 112. The communication link 130 between the device402 and terminal 410 may be identical to the link 130 shown in FIG. 1.

In addition to the communication port 106, the device 402 may furthercomprise a receiver 406. In addition to the communication port 112, theterminal 410 may further comprise a receiver 412. The receivers 406 and412 may be configured to receive signals from the time provider 430, asshown on FIG. 4A. In some embodiments, the time provider 430 may be aprecise time provider, such as a GPS satellite network (with signalcoming either from the same GPS satellite, or from different GPSsatellites), and receivers 406 and 412 may be GPS signal receivers. Insome embodiments, instead of GPS, other standard timing signals, such asWWVB time signal provided by National Institute of Standards andTechnology (NIST) in the United States or MSF time signal in the UnitedKingdom may be used. And the receivers 406 and 412 may be correspondingsignal receivers for those timing signals.

FIG. 4B illustrates an exemplary method 450 according to one embodimentof the present disclosure. The method 450 may be used by an embodimentof the terminal 410 to determine whether there are any delays on thecommunication link 130 between the device 402 and the terminal 410. Atblock 452, the terminal 410 may establish the communication link 130with the device 402 as described above with respect to block 222. Atblock 454, the terminal 410 may send data to the device 402, and recorda sending time received from the time provider 430. In some embodiments,the sending time may be a precise time provided by the time provider 430at the exact moment the data is sent.

FIG. 4C is a flow diagram illustrating an exemplary method 460 for thedevice 402 to respond to the data sent by the terminal 410 according tothe present disclosure. As shown in FIG. 4C, at block 462, the device402 may establish the communication link 130 with the terminal 410. Asdescribed above, the details of establishing such a data connection maydepend on the particular type of communication link 130 used in aparticular implementation and an optional logical channel over thecommunication link 130 may be established. At block 464, the device 402may receive the data sent by the terminal 410 and record a receivingtime received from the time provider 430. In some embodiments, thereceiving time may be a precise time provided by the time provider 430at the exact moment the data is received. In some other embodiments,this time may be calculated based on the precise time provided by thetime provider 430 prior to the moment that the data is received. Forexample, the time provider 430 may transmit signals with precise timevalues periodically (e.g., each second). The device 402 may calculatethe time passed since the last precise time value has been received andadd the calculated time to the last received precise time value toobtain the precise time when the data is received. At block 466, thedevice 402 may send the receiving time to the terminal 410. In someembodiments, for example, the receiving time may be sent over the securecommunication channel.

Referring back to the method 460 in FIG. 4B, at block 456, the terminal410 may receive the reply from the device 402. In some embodiments, thereply may include the receiving time recorded at the device 402. Atblock 458, the terminal 410 may process the reply to determine whetherthere is an unreasonable delay in the communication link 130. Forexample, using the sending time recorded at the terminal 410 and thereceiving time included in the reply from the device 402, the terminal410 may calculate the time period it takes for data transmission fromthe terminal 410 to the device 402. If this time period is greater thana predefined time threshold, this may indicate that there are delayswith the data transmission on the link 130, which, in turn, may indicatethat there may be a relay attack against that link. In some embodiments,a sending time may be included into the data sent from the terminal 410,and the time period may be calculated by the device 402 and thethreshold optionally checked also by the device 402.

It should be noted that in some embodiments methods 440/450 may berepeated more than one time to ensure that delays in data transmissionare not due to occasional communication errors and/or processing errorsat the device 402 and/or the terminal 410.

FIG. 5A shows a system 500 according to one embodiment of the presentdisclosure. The system 500 may comprise a device 502 and a terminal 510.The device 502 may be an embodiment of the device 102 and contains allfeatures of the device 102 including the communication port 106. Inaddition, the device 502 may further comprise a computation module 504.The terminal 510 may be an embodiment of the terminal 110 and containsall features of the terminal 110 including the communication port 112.In addition, the terminal 510 may further comprise a timer (or counter)514 and a processor 516. Although the timer (or counter) 514 is shown asa separate component, in certain embodiments, the timer 514 may beimplemented as part of the processor 516 (e.g., in software orhardware), or may be integrated into other components of the terminal510. The communication link 130 between the device 502 and terminal 510may be identical to the link 130 shown in FIG. 1. The computation module504 may be used for fast computation of functions (e.g., cryptographicalfunctions) related to detection of relay attacks that are discussedherein.

FIG. 5B illustrates an exemplary method 520 that may be implemented bythe terminal 510 to check whether a relay attack is mounted against itscommunication with the device 502. The method 520 may start at block522, at which the terminal 510 may establish the communication link 130with the device 502 to communicate data between the device and theterminal. As described above, the details of establishing such a dataconnection may depend on the particular type of communication link 130used in a particular implementation and an optional logical channel overthe communication link 130 may be established.

At block 524, a nonce may be generated. For example, a cryptographicallysafe random number generator (implemented in hardware, not shown, orimplemented in software running on the processor 516) may be used forthis purpose. At block 526, the generated nonce may be sent to thedevice 502 as a request and the timer 514 may be started to count timefrom when the nonce is sent.

The device 502 may implement an exemplary method 540 shown on FIG. 5C toprocess the request. At block 542, the device 502 may receive the nonce.Then at block 544, the device 502 may compute a verification value usinga predefined function. The predefined function may use both a privatekey of the device 502 and the received nonce to calculate theverification value. In some embodiments, the predefined function may beselected such that all bits of the nonce are necessary to start thecomputation, and the resulting bits are obtained simultaneously. Forexample, in one non-limiting embodiment, the predefined function may bean encryption of the nonce with the private key of the device 502 by thecomputation module 504. Then the method 540 may proceed to block 546, atwhich the verification value may be sent back to the terminal 510 as aresponse.

Referring back to FIG. 5B, after sending the nonce to the device 502,the exemplary method 520 may proceed from block 526 to block 528, atwhich a value may be received by the terminal 510. As described abovewith respect to FIG. 5C, the received value may be the verificationvalue generated by the device 502 using the predefined function. Atblock 529, the time at which the value is received is determined and atime duration between when the nonce was sent and the value received isdetermined or calculated.

At block 530, the time duration between the nonce being sent and theverification value being received is compared to a predefined timethreshold T_(th). If the time between the nonce being sent and theverification value being received exceeds the predefined time threshold,this may indicate that the computation was performed by a device locatedat a distance greater than expected (or permitted) and the method mayproceed to block 538 (or optionally to block 534). This may indicatethat the link 130 is under a relay attack.

If the time between the nonce being sent and the verification valuebeing received is within the predefined time threshold, the method 520proceeds to block 531 at which the received verification value may beprocessed. The processing may be performed by the terminal 510 usingprocedures specific to the predefined function used by the device 502.

In an embodiment, if the predefined function used by the device 502 isto encrypt the nonce using the private key of the device 502 (asdescribed above with respect to block 544), the processing may be doneusing a function that decrypts the received value using the public keyof the device 502. The decrypt function may decrypt the received valueto recover the nonce. For example, in some embodiments, the terminal 510may obtain a public key of the device 502, and ensure that the publickey is properly certified by a trusted third party (e.g., a certificateauthority). Such certification may mean that this public key correspondsto a specific private key, which belongs to a trusted device.Accordingly, based on the certification of the public key and theassumption that a trusted device does not expose its private key to anythird parties, it can be assumed that calculation of the predefinedfunction has actually been done at the trusted device and not somewhereelse.

It should be noted that the public key of the device may be obtained atany time prior to or after receiving the verification value, as long asit is received before the processing of block 531 begins. For example,the public key may be stored in a volatile or non-volatile storage ofthe terminal 510 after it has been received during a previouscommunication session between the terminal 510 and a trusted thirdparty, or may be installed on the terminal 510 by the vendor of theterminal 510.

At block 532 the decrypted value may be compared to the nonce sent tothe device 502. If they are the same, at block 536 the method 520 maydetermine that the relay attack detection has passed with no relayattack detected. Passing the relay attack detection at block 536 may beinterpreted as “the owner of the private key that corresponds to thepublic key used in block 531 is on the other end of the logical channelestablished in block 522, and no relay attack on the channel has beendetected”. This may indicate that the link 130 is not under a relayattack. In some embodiments, if the communication between the twocommunicating parties is through a protected logical channel (such asSSL/TLS connection(s) over the communication link), the process 520 mayprovide strong relay attack detection and authentication assurances.

If either the time check at block 530 or the validation determination atblock 532 fails, the method 520 may proceed to block 528, at which themethod 300 may determine that the link 130 is under a relay attack. Forexample, if the time check at block 530 or the validation determinationat block 532 fails, the terminal 510 may determine that there is apossibility that the communication link 130 or the logical channelestablished over the communication link 130 has been compromised or thatthe device 502 may be a fake device.

In one or more embodiments, to handle occasional communication errors,the method 520 may attempt to repeat the blocks 524-532 as indicated byblock 534, which may be optional. In some embodiments, the number ofretransmission attempts may be limited (for example, to a number like 3or 5 times).

Because the amount of time spent on calculation of the predefinedfunction at the device 502 may affect the value of T_(th), someembodiments may use a function that can be computed faster thanasymmetric encryption using a private key. It should be noted that bothencryption and decryption of the nonce using asymmetric cryptography maytake time in the order of tens of milliseconds. Thus, in someembodiments, another predefined function with a faster computing speedmay be implemented. For example, a predefined function that utilizes twoparameters may be used such that one parameter may be the nonce, and theother may be a parameter V, which may be generated (in some embodiments,randomly) by the device 502.

In one embodiment, the other predefined function may be a symmetricencryption function that uses the parameter V as the encryption key fora symmetric encryption of the nonce. The symmetric encryption, forexample, may be implemented to complete within 10 microseconds, which islikely to be several orders of magnitude less than the asymmetricencryption of the same nonce. In another embodiment, the otherpredefined function may be a hash function that computes a hash value ofa concatenation of the nonce and the parameter V. It is to be understoodthat these embodiments are merely exemplary and that the scope of thepresent invention is broad enough to encompass any appropriate presentlyknown or future-developed functions.

FIG. 6A shows another exemplary system 600 according to the presentdisclosure. The system 600 may comprise a device 602 and a terminal 610.The device 602 may be an embodiment of the device 102 and contains allfeatures of the device 102 including the communication port 106. Inaddition, the device 602 may further optionally comprise a private key604 and a crypto engine 608. The optional private key 604 may be storedin a non-volatile storage (not shown) of the device 602. The terminal610 may be an embodiment of the terminal 510 and contains all featuresof the terminal 510 including the communication port 112, the timer 514and the processor 516. In addition, the terminal 610 may furtheroptionally comprise a crypto engine 618. The communication link 130between the device 502 and terminal 510 may be identical to the link 130shown in FIG. 1.

In embodiments where the crypto engines 608 and 618 are present, theymay be implemented in hardware, software, or combination of hardware andsoftware. Moreover, in some embodiments, the functionality of the cryptoengine 618 may be implemented by the processor 516 either in hardware orsoftware and a separate crypto engine 618 may not be necessary.

FIG. 6B illustrates an exemplary method 620 that may be implemented bythe terminal 610 to check whether a relay attack is mounted against itscommunication with the device 602. The method 620 may start at block622, at which the terminal 610 may establish the communication link 130with the device 602 to communicate data between the device and theterminal. As described above, the details of establishing such a dataconnection may depend on the particular type of communication link 130used in a particular implementation and an optional logical channel overthe communication link 130 may be established.

At block 624, a nonce may be generated. For example, a cryptographicallysafe random number generator implemented in hardware (not shown) orimplemented in software running on the processor 516 may be used forthis purpose. At block 626, the generated nonce may be sent to thedevice 602 and the timer 514 may be started to count time from when thenonce is sent.

The device 602 may implement an exemplary method 650 shown in FIG. 6Ccorresponding to the exemplary method 620. At block 652, the device 602may receive the nonce. At block 654, the device 602 may generate a valueV. In one embodiment, the value V (which may also be referred to as theparameter V) may be generated using a random number generator (notshown) and may be a random number that cannot be predicted and/orcomputed outside the device 602. In some embodiments, to speed up theprocessing within block 654, the value V may be pre-generated (as longas it is not previously disclosed outside the device 602). At block 656,the value V (also referred to as a verification value) may be sent tothe terminal 610.

Referring back to the exemplary method 620 on FIG. 6B, at block 628, theterminal 610 may receive the verification value from the device 602, andat block 629 may determine the time τ elapsed from sending the nonceuntil receiving the verification value. At block 630, the time τ may becompared to a predefined time threshold T_(th). Setting an appropriatetime threshold T_(th) may significantly reduce or eliminate thepossibility of a man-in-the-middle attack as described above, orvariations thereof. For example, if it is known that, without a relayattack, processing according to the discussed method (that is, timebetween sending a nonce and receiving the verification value V) requires2 milliseconds, and with a relay attack, the same would take at least 6milliseconds, then setting T_(th) in the range of 3-5 milliseconds mayhelp detection of relay attacks (as time will be greater than T_(th))while connections without relaying may pass the check. If theverification value is not received within the predefined time thresholdT_(th), then, from block 630, the method 620 may proceed to block 638(or, optionally, to block 634).

The exemplary method 650 of FIG. 6C, in the meantime, may proceed fromblock 656 to block 658, at which, the device 602 may compute a secondaryvalue. The secondary value may be generated from the value of the noncereceived at block 652 and the value V. In one non-limiting example, thesecondary value may be a concatenation of the nonce and the value V. Insome embodiments, the secondary value may additionally include someother information, such as, for example, current date and time, timespent by the device 602 on processing the request, and/or other values.

In some embodiments, the secondary value may be signed and/or encryptedwith the private key 604 of the device 602. The signing or encryption atthe device 602 may be performed, for example, by the optional cryptoengine 608 or by a processor (or a computation module) of the device 602(not shown). At block 660, the device 602 may send the secondary valueto the terminal 610. If the secondary value is signed or encrypted bythe device 602, the secondary value may be sent with the signature or inits encrypted form.

It should be noted that while operations within block 658 may take asignificant amount of time (for example, on the order of 0.01 to 0.1second), it does not affect T_(th), which may be limited only by thespeed of block 654.

Referring back to the exemplary method 620 in FIG. 6B, if at block 630,it is determined that the verification value is received within thepredefined time threshold T_(th), the method 620 may proceed to block631, at which the terminal 610 may receive the secondary value. Then, atblock 632, the terminal 610 may process the verification value and thesecondary value by performing the exemplary processes shown in blocks642, 644 and 646. For example, at block 642, using a public key of thedevice 602 (e.g., the public key corresponding the optional private key604), the terminal 610 may verify the signature of (or decrypt) thereceived secondary value. At block 644, the value of the nonce sent tothe device 602 may be compared to the value of the nonce received aspart of the secondary value from the device 602. At block 646, theterminal 610 may verify the secondary value, for example, by comparingthe value V received at block 628 to the value V received as a part ofthe secondary value received at block 631.

If all the checks in blocks 642-646 are successful, at block 633 thevalidation may be determined to be successful and the method 620 mayproceed to block 636, at which the method 620 may determine that therelay attack detection has passed with no relay attack has beendetected. If either the time check at block 630 or the validationdetermination at block 663 fails (for example, because of failing of anyone of the checks at blocks 642-646), the method 620 may proceed toblock 638 (or optionally block 634), at which the method 620 maydetermine that a relay attack has been detected.

Passing the relay attack detection at block 636 may be interpreted as“the owner of the private key that corresponds to the public key used inblock 631 is on the other end of the communication link established inblock 622, and no relay attack on the channel has been detected.” Insome embodiments, if the communication between the two communicatingpartners is through a protected channel (such as SSL/TLS connection(s)over the communication link), the method 620 may provide strong relayattack detection and authentication assurances.

Those with skill in the art understand that, in some embodiments,components necessary for the method 620 may be implemented by the device602 and the device 602 may initiate the method 620 to ensure that norelay attack is mounted against the link 130 with the terminal 610, too.In those embodiments, the terminal 610 may also implement the necessarycomponents of the device 602 for the method 650. In certain embodiments,the same methods 620 and 650 may be performed by both sides of acommunication link for mutual detection of relay attacks.

It should further be noted that, when signature of the secondary valueis used, in some embodiments the signature may be implemented byencrypting the whole or a part of the secondary value by the private keyof the device 602; in this case the signature verification may beimplemented as decryption using a public key that corresponds to theprivate key of the device 602.

In some embodiments, a method based on combining the method 600 withreporting the time T_(d) spent by the device 602 on message processingmay be used. The time period T_(d) may represent the duration(expressed, for example, in terms of microseconds) of time from when thenonce is received till when the verification value V is sent. Forexample, in one embodiment, T_(d) may represent the duration of timefrom when the last bit of the nonce is received till when the first bitof the verification value V is sent. For example, in one of suchembodiments, the terminal 610 may determine the threshold T_(th) in thesoftware that sends the request and receives the response (for example,within a process or software application executed by a computerprocessor running on the terminal 610). The time T_(d) may be measuredat the device 602 by the software that receives the request and sendsback the response (for example, by a process or a software applicationexecuted by a computer processor running on the device 602). In some ofsuch embodiments, T_(th) may be alternatively calculated, for example,as T_(th)=T_(d)+T_(term)+T_(dev), where T_(d) may be received from thedevice 602 (for example, calculated at the application level as the timebetween receiving a request and sending a response in software),T_(term) may represent typical (or maximum) time delays at the terminal610, and T_(dev) may represent typical (or maximum) unaccounted timedelays (outside of interval T_(d)) at the device 602. In someembodiments, T_(dev) may depend on the type of the device 602. Forexample, the terminal 610 may have (or have access to) a databasestoring T_(dev) (DBT, not shown) for each of known type of the device602. The type of the device 602 may be derived, for example, from apublic key of the device 602. In one non-limiting example, the terminal610 may search a database of public keys (DBK, not shown) and locate thetype of the device 602 based on the public key of the device 602.Alternatively, the device 602 may send its type to the terminal 610, forexample, as an additional field in the secondary value, which may besigned by the private key of device 602. In some embodiments, instead ofusing the databases DBT and/or DBK, the terminal 610 may send a requestto a server (not shown) to obtain necessary information.

In one non-limiting exemplary embodiment, the terminal 610 may be a POSterminal, and the device 602 may be a payment device such as acontactless smartcard or an NFC-enabled phone. The terminal 610 may sendto and receive from the device 602 usual smartcard Application ProtocolData Unit (APDU) requests/responses. At least some of the usualrequests/responses may include authentication data, such as a digitalsignature or message authentication code (MAC) generated by the device602. A special APDU request/response may be added after one or more ofsuch usual APDU requests/responses. The response in this special APDUrequest/response may include the time T_(d) for a previous usual APDUrequest/response. In some embodiments, the time T_(d) may be signed ormay have an associated MAC generated by the device 602. Moreover, insome embodiments, the signature or the associated MAC may be generatedusing a unique identifier of the previous usual APDU request.

In some embodiments, it may be necessary to include the uniqueidentifier of the previous usual request into signature/MAC calculationto avoid replay attacks in which an attacker may try to use a previouslyrecorded special APDU with T_(d) associated with a different APDUrequest/response. It should be understood that in such embodiments allrequests may be unique. To achieve this, each APDU request, in additionto other data, may, for example, have a nonce as one of its fields. Theunique identifier may be, for example, a hash value of the request, orthe nonce.

The time T_(d) may be included into APDU responses in a number of ways.For example, in some cases T_(d) for a preceding APDU may be includedinto a subsequent response of a special APDU request/response.Alternatively, a usual APDU request/response may be extended to containT_(d) for the previous APDU request/response pair. In anotheralternative, an APDU response may include an estimate of timing foritself as an upper-bound estimate by the device 602, and the device 602may wait until the estimated time elapses (at application level) beforesending the APDU response.

In some embodiments, the terminal 610 may set T_(th), for example,between T_(d)+10 ms and T_(d)+50 ms, with the number of retransmissionattempts (similar to that of a block 634) limited to a number from 3 to5. In any case, similar to the method 600 above, the terminal 610 maydeny payment if T_(th) is exceeded.

In yet another embodiment, based on method 600 described above, twospecial APDU request/response pairs may be used. In the request of thefirst special APDU request/response pair the terminal 610 may send anonce, and in the response of the first special APDU request/responsepair the device 602 may send a verification value. The device 602 maymeasure the time T_(d) spent on preparation of this response and includethe measured T_(d) in the response of the second special APDUrequest/response pair. In this embodiment, no modification to usualAPDUs (such as adding nonces) is necessary.

In a yet another non-limiting exemplary embodiment, the terminal 610 maybe a POS terminal, and device 602 may be a payment device such as acontactless smartcard or an NFC-enabled phone. To perform relay attackdetection, a method, similar to method 620 described above, may be usedas follows. The terminal 610 may send and receive usual smartcard APDUrequests/responses, setting T_(th), for example, to a fixed numberdepending on the nature of the APDU request. The T_(th) may be setaccording to APDU commands, which may include some kind of signature (orMAC) generated by the device 602. In some embodiments, T_(th) may bepre-set, for example, to a value between 100 and 300 ms for an APDUrequest that requires calculating a signature or MAC. In someembodiments, the device 602 may wait for a pre-defined time (forexample, T_(th)−50 ms to T_(th)−10 ms) before sending such APDUresponses. Waiting by the device 602 for a pre-defined time may ensurethat processing of all requests take roughly the same time regardless ofcomputational capabilities of the device 602. In such embodiments, ifthe terminal 610 receives the response before the pre-defined time, itmay indicate that the device 602 does not wait as expected, andtherefore may be compromised and correspondingly, the terminal 610 mayrefuse further communication.

In yet another embodiment, T_(th) may be a function of the device typeof the device 602. The terminal 10 may determine the type of the device602 as described above, for example, by receiving it from the device 602or looking up the type information in some external database based on apublic key of the device 602. Based on the device type, for example,T_(th) may be set to lower values for faster-performing devices and tohigher values for slower-performing devices. In some other embodiments,T_(th) may be a function of both the type of the device 602 and thenature of the command. Again, as an additional protective measure, ifthe terminal 610 receives the response faster than expected for such adevice and/or command, the device 602 or the communication channel maybe deemed compromised, and the terminal 610 may terminate communication.

It should be noted that other processes of relay attack detection may beused in place of or in addition to the methods described above. Forexample, exemplary processes for establishing proximity may includethose described in U.S. Provisional Patent Application 61/825,376, filedMay 20, 2013, entitled “Systems, Methods and Apparatuses for EnsuringProximity of Communication Device” (the '376 Application), the entirelyof which is incorporated by reference.

Embodiments of the present disclosure may implement one or more of therelay attack detection methods described above. For example, in someembodiments, the terminal 110 (hereinafter may refer to any of theterminals 110, 210, 310, 410, 510 and 610) and the device 102(hereinafter may refer to any of the devices 102, 202, 302, 402, 502 and602) may implement one or more of the tests described above. Inaddition, the terminal 110 and the device 102 may implement other relayattack detection methods, for example, based on methods described in the'376 Application. Moreover, other methods, such as precise positiondetermining (such as GPS) may also be implemented by either or both theterminal 110 and the device 102. In some other embodiments, while theterminal 110 may implement a wide variety of tests to assure absence ofrelay attacks, the device 102 may support only a subset of these testsor a different set of tests. It should be noted that support by thedevice 102 may mean that the device 102 implements a methodcorresponding to the relay attack detection method implemented at theterminal 110. For example, if the terminal 110 implements the method620, the device 102 may support this method if it implements thecorresponding method 650.

FIG. 7 shows an exemplary method 700 according to one embodiment of thepresent disclosure. The method 700 may start at block 702, at which aterminal 110 may establish a communication link 130 with a device 602 tocommunicate data between the device and the terminal. As describedabove, the details of establishing such a data connection may depend onthe particular type of communication link 130 used in a particularimplementation and an optional logical channel over the communicationlink 130 may be established.

At block 704, the terminal 110 may obtain from the device 102 a firstlist of relay attack detection methods supported by the device 102. Forexample, the device 102 may support one or more of the relay attackdetection methods that may be implemented at the terminal 110 asdescribed above but not all of them. At block 706, the terminal 110 maycreate a second list of relay attack detection methods that are bothimplemented by the terminal 110 and supported by the device 102. Forexample, the terminal 110 may maintain a complete list of relay attackdetection methods implemented by the terminal 110. Upon receipt of thefirst list of relay attack detection methods received from the device102, the terminal 110 may determine which one of complete list of therelay attack detection methods implemented by the terminal 110 is alsosupported by the device 102. Thus, the second list of the relay attackdetection methods may include all relay attack detection methods thatare implemented by the terminal 110 and supported by the device 102.

In some embodiments, the relay attack detection methods may be weighted.For example, each relay attack detection method may be assigned a weightsuch that methods of greater precision and/or reliability may havegreater weight than methods with lower precision and/or reliability. Forexample, the relay attack detection method 620 and its correspondingmethod 650 may be more precise than the relay attack detection method220 and its corresponding method 240. If the relay attack detectionmethods are weighted, in some such embodiments, the second list of relayattack detection methods may be optionally filtered. For example, ifthere are both low-weight and high-weight methods on the list, some orall low-weight methods may be filtered out in some embodiments.

At block 708, the terminal 110 may perform the relay attack detectionmethods in the second list. The methods may be performed sequentially,in parallel, or a combination of these two approaches. In someembodiments, if the second list of methods are filtered, then only thoseleft may be performed. At block 710, the terminal 110 may determinewhether there is a relay attack based on the relay attack detectionresults. For example, if there is a potential relay attack ongoing, theresults of the tests performed in block 708 may indicate an unreasonabledelay in the link 130.

In one embodiment, if more than one relay attack detection method havebeen performed at block 708 and at least one method indicates apotential relay attack, the terminal 110 may determine that thecommunication link 130 between the terminal 110 and the device 102 isunder a relay attack.

In another embodiment, according to the weights assigned to relay attackdetection methods, a final determination at block 710 may be based onthe results of methods with greater weights while discarding results ofless reliable or precise methods. In yet another embodiment, a finaldetermination at block 710 may be based on a relay attack detectionmethod with the greatest weight only.

In yet another embodiment, a final determination at block 710 may dependon whether the total weight of passed relay attack detection methodsreaches a pre-defined total weight threshold. That is, if only a fewlow-weight tests indicate that no relay attack is mounted against link130, a final determination at block 710 may still deem that there may bea relay attack on the link 130 even in absence of any relay attackdetection result indicating there is a relay attack.

In some embodiments, two possible weights may be assigned to each of therelay attack detection methods performed at block 708—one weight forsuccessfully completed relay attack detections in which no attack isdetected, and another weight for relay attack detections indicating thatan attack may be in progress. These weights may be, for example, addedindependently for all relay attack detection methods performed andcompared to two separate pre-defined thresholds to determine the overalloutput of the relay attack detection. In some embodiments, these weightsmay be added together and compared to a single threshold. In some otherembodiments, for example, weights for “no relay attack detected”outcomes may be positive, and weights for “relay attack detected”outcomes may be negative, and all weights may be added together andcompared with a single threshold to determine the overall outcome of therelay attack detection.

In some embodiments, each relay attack detection test itself maygenerate weights for the test result. For example, a value of minus one(“−1”) may mean “attack is certainly ongoing,” a value of plus one(“+1”) may mean “attack is proven impossible”, and a value of zero (“0”)may mean “no information about attack has been extracted.” These weightsmay be used in addition to or instead of weights assigned to relayattack detection methods as described above.

There are a variety of ways to assign weights to the relay attackdetection methods according to the present disclosure. For example, insome embodiments, the device 102 may support two methods: 240 and 650.To continue the example, the terminal 110 may be configured such thatfailure of the method 240 has an assigned weight of −1000, success ofthe method 240 has an assigned weight of 100, failure of the method 650has an assigned weight of −10000, and success of the method 650 has anassigned weight of 500. In this example, the threshold may be set atzero, and thus if the sum of weights is greater than zero, the overalloutcome of the relay attack detection may be “no relay attack detected.”Accordingly, if both methods 240 and 650 succeed, the overall outcome ofthe relay attack detection is “no relay attack detected” because 100+500is larger than zero. If the method 650 succeeds, and the method 240fails, the overall outcome of the relay attack detection may be “relayattack detected” because −1000+500=−500, which is less than zero.Similarly, if the method 240 succeeds and the method 650 fails, theoverall outcome of the relay attack detection may be “relay attackdetected” because 100+(−10000)=−9900, which is less than zero. If bothmethods fail, the overall outcome of the relay attack detection may alsobe “relay attack detected” because −1000+(−10000)=−11000, which is lessthan zero.

In some other embodiments, weights for different outcomes of the method240 may be assigned as follows. If the lists of the WiFi terminals fromwhich the signal may be received by the terminal 110 and the device 102,respectively, fully match, the outcome of the method 240 may be assigneda weight of 100. If the lists of the WiFi terminals diverge for at most10%, that is, for example, only a single entry out of 10 could not bematched, the weight is 0. If the lists diverge for at most 20%, that is,for example, at most two entries out of 10 could not be matched, theweight is −200. And, if the divergence is more than 20%, the weight is−1000. Weights for the method 650 may also be assigned as describedabove. Then, if the method 650 succeeds, and lists of the method 240diverge for 20% or less, the overall outcome of the relay attackdetection may be “no relay attack detected” because 500+(−200), which islarger than zero, and −200 is the lowest possible weight in this case.If the lists diverge for more than 20%, the overall outcome of the relayattack detection may be “relay attack detected” because 500+(−600) isless than zero. The weights assignments described herein are merelyexemplary and other weight assignments may be implemented in addition toor in place of these exemplary weight assignments.

It should be understood that any methods or blocks discussed above to beimplemented by the terminal 110 may be implemented by the device 102.Also, any methods or blocks discussed to be implemented by the device102 may be implemented by the terminal 110. In some of such embodiments,the device 102 may make a decision of whether a relay attack is mountedagainst the communication link 130.

While specific embodiments and applications of the present inventionhave been illustrated and described, it is to be understood that theinvention is not limited to the precise configuration and componentsdisclosed herein. The terms, descriptions and figures used herein areset forth by way of illustration only and are not meant as limitations.Various modifications, changes, and variations which will be apparent tothose skilled in the art may be made in the arrangement, operation, anddetails of the apparatuses, methods and systems of the present inventiondisclosed herein without departing from the spirit and scope of theinvention. By way of non-limiting example, it will be understood thatthe block diagrams included herein are intended to show a selectedsubset of the components of each apparatus and system, and each imagedapparatus and system may include other components which are not shown onthe drawings. Additionally, those with ordinary skill in the art willrecognize that certain steps and functionalities described herein may beomitted or re-ordered without detracting from the scope or performanceof the embodiments described herein.

The various illustrative logical blocks, modules, circuits, andalgorithm steps described in connection with the embodiments disclosedherein may be implemented as electronic hardware, computer software, orcombinations of both. To illustrate this interchangeability of hardwareand software, various illustrative components, blocks, modules,circuits, and steps have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. The described functionalitycan be implemented in varying ways for each particular application—suchas by using any combination of microprocessors, microcontrollers, fieldprogrammable gate arrays (FPGAs), application specific integratedcircuits (ASICs), and/or System on a Chip (SoC)—but such implementationdecisions should not be interpreted as causing a departure from thescope of the present invention.

The steps of a method or algorithm described in connection with theembodiments disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, a DVD or any other form of storage medium known in the art.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of thepresent invention. In other words, unless a specific order of steps oractions is required for proper operation of the embodiment, the orderand/or use of specific steps and/or actions may be modified withoutdeparting from the scope of the present invention.

1-34. (canceled)
 35. A method for an apparatus to determine whetherthere is a relay attack on a communication link between the apparatusand a device, the method comprising: establishing, by the apparatus, acommunication link with the device via a communication port of theapparatus; receiving, by the apparatus via the communication link, fromthe device a first list of at least one relay attack detection methodthat the device is configured to execute; generating, by the apparatus,a second list of one or more relay attack detection methods that theapparatus and the device are each configured to execute based on thefirst list received from the device; executing, by the apparatus, atleast one of the relay attack detection methods of the second list; anddetermining, by the apparatus, whether there is a relay attack on thecommunication link according to at least one result generated by the atleast one of the relay attack detection methods of the second listexecuted by the apparatus.
 36. The method of claim 35, wherein each ofthe one or more relay attack detection methods of the second list isassociated with a weighted-value.
 37. The method of claim 36, furthercomprising filtering from the second list, by the apparatus, a firstrelay attack detection method from the one or more relay attackdetection methods of the second list based upon a respectiveweighted-value of the first relay attack detection method.
 38. Themethod of claim 36, further comprising: receiving, by the apparatus, atleast a first result from a first relay attack detection method of thesecond list executed by the apparatus and a second result from a secondrelay attack detection method of the second list executed by theapparatus; and discarding, by the apparatus, at least the first resultor the second result based upon the weighted-value associated with eachof the first and second relay attack detection methods.
 39. The methodof claim 36, further comprising: receiving, by the apparatus, a resultfrom each respective relay attack detection method of the second listexecuted by the apparatus; and determining, by the apparatus, a totalweight value based on each result indicating no relay attack detectedfor each respective relay attack detection method; and determining, bythe apparatus, whether the total weight value satisfies a threshold. 40.The method of claim 35, wherein the apparatus executes each of the atleast one of the relay attack detection methods of the second list inparallel.
 41. The method of claim 35, wherein the apparatus sequentiallyexecutes each of the at least one of the relay attack detection methodsof the second list.
 42. The method of claim 35, wherein the apparatusdetermines that the relay attack is on the communication link based inpart on a delay on the communication link.
 43. The method of claim 35,wherein the apparatus executes at least two relay attack detectionmethods from the second list, and wherein the apparatus determines thatthe relay attack is on the communication link when at least one of theat least two relay attack detection methods executed generates a resultindicating the relay attack is on the communication link.
 44. Anapparatus for determining whether there is a relay attack, the apparatuscomprising: a communication port; and a processor configured to:establish a communication link with a device via the communication port;receive from the device via the communication link a first list of atleast one relay attack detection method that the device is configured toexecute; generate a second list of one or more relay attack detectionmethods that the apparatus and the device are each configured to executebased on the first list received from the device; execute at least oneof the relay attack detection methods of the second list; and determinewhether there is a relay attack on the communication link according to aresult generated by the at least one of the relay attack detectionmethods of the second list executed by the processor.
 45. The apparatusof claim 44, wherein each of the one or more relay attack detectionmethods of the second list is associated with a weighted-value.
 46. Theapparatus of claim 44, wherein the processor is further configured tofilter from the second list a first relay attack detection method fromthe one or more relay attack detection methods of the second list basedupon a respective weighted-value of the first relay attack detectionmethod.
 47. The apparatus of claim 46, wherein the processor is furtherconfigured to: receive at least a first result from a first relay attackdetection method of the second list executed by the processor and asecond result from a second relay attack detection method of the secondlist executed by the processor; and discard at least the first result orthe second result based upon the weighted-value associated with each ofthe first and second relay attack detection methods.
 48. The apparatusof claim 46, wherein the processor is further configured to receive aresult from each respective relay attack detection method of the secondlist executed by the processor; and determine a total weight value basedon each result indicating no relay attack detected for each respectiverelay attack detection method; and determine whether the total weightvalue satisfies a threshold.
 49. The apparatus of claim 44, wherein theprocessor executes each of the at least one of the relay attackdetection methods of the second list in parallel.
 50. The apparatus ofclaim 44, wherein the processor sequentially executes each of the atleast one of the relay attack detection methods of the second list. 51.The apparatus of claim 44, wherein the processor determines that therelay attack is on the communication link based in part on a delay onthe communication link.
 52. The apparatus of claim 44, wherein theprocessor executes at least two relay attack detection methods from thesecond list, and wherein the processor determines that the relay attackis on the communication link when at least one of the at least two relayattack detection methods executed generates a result indicating therelay attack is on the communication link.